While Opress was subjected to brutal Sith training under Dooku's charge, Ventress prepared to pit the monstrous Nightbrother against Dooku. Yet when Ventress's plans for revenge culminated at Toydaria, she and her ex-Master found that neither of them could contain Opress's impulsive nature and rage. In what became a three-way lightsaber battle, Opress overcame Ventress's spell of control and also terminated his service to Dooku, further battling his way through Jedi KnightAnakin Skywalker and Jedi MasterObi-Wan Kenobi before escaping to Dathomir. After learning from Talzin of his kinship to the former Sith apprentice DarthMaul,[7] Opress rescued his weakened brother from the depths of Lotho Minor[10] and brought him home to Dathomir, where Talzin restored his mind and body. Opress then became involved with Maul's pursuit of vengeance on Kenobi, who had cut him in half over a decade ago in the Theed Royal Palace, on Naboo. Although Kenobi escaped from them with the aid of Asajj Ventress during a confrontation at Raydonia,[11] Opress and Maul continued their plans for revenge and galactic domination, turning to the criminal underworld to achieve their needs. Opress and Maul cut a swath through the Outer Rim, battling through civilians and Jedi Knights alike who stood in their way. As part of Maul's plans, Opress became a Sith Lord, but he was forced to become the apprentice—submitting to his brother, the Master—in accordance with the Sith Rule of Two. While attempting to recruit Weequaypirates into their service on Florrum, Opress killed renowned Jedi Master Adi Gallia, though he soon thereafter lost his left arm to Kenobi's lightsaber.[8]

Kenobi then chased Opress and Maul off Florrum, destroying their ship and leaving them stranded until they were discovered by members of the Death Watch, a group of Mandalorian warriors led by Pre Vizsla. Opress, Maul, the Mandalorians, and various criminal groups in the galaxy, including Black Sun, Pyke Sindicate, and Hutts formed an alliance to overthrow the pacifist rulers of the planet Mandalore,[6] and even though the operation ended successfully, Viszla and his men arrested Opress and Maul. After breaking free from prison with Mandalore's incarcerated Prime Minister, Almec, Opress and Maul seized control of Mandalore after Maul killed Viszla in lightsaber combat.[12] Their rule of Mandalore attracted unwanted attention from Maul's former Master, Darth Sidious, who saw the power of the two Sith brothers as a threat to the dominance of his Sith Order. Sidious traveled to Mandalore and confronted the two, fatally impaling Opress, who in his dying breath expressed regret for never having been Maul's equal. As he died, a green mist emanated from his body and his armor disappeared. His muscles and physique reverted back to their form from before the Nightsister ritual.[2]

↑Although Opress's Encyclopedia entry lists his height as 1.89 meters, this is significantly lower than that of Dooku, whose height is given as 1.93 meters. Since the post-transformation Opress is portrayed as being taller than Dooku in "Monster," this article assumes that Opress's Encyclopedia height refers to his pre-transformation height.